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At least 199 records · Page 11Linked to original sources
PubMed2006

Electrochemical treatment of Procion Black 5B using cylindrical flow reactor--a pilot plant study.

The paper presents the results of an efficient electrochemical treatment of Procion Black 5B--a pilot plant study. Experiments were conducted at different current densities and selected electrolyte medium using Ti/RuO2 as anode, stainless-steel as cathode in a cylindrical flow reactor. By cyclic voltammetric analysis, the best condition for maximum redox reaction rate was found to be in NaCl medium. During the various stages of electrolysis, parameters such as COD, colour, FTIR, UV-vis spectra studies, energy consumption and mass transfer coefficient were computed and presented. The experimental results showed that the electrochemical oxidation process could effectively remove colour and the chemical oxygen demand (COD) from the synthetic dye effluent. The maximum COD reduction and colour removal efficiencies were 74.05% and 100%, respectively. Probable theory, reaction mechanism and modeling were proposed for the oxidation of dye effluent. The results obtained reveal the feasibilities of application of electrochemical treatment for the degradation of Procion Black 5B.

Electrodes↗
PubMed2004

A new method of solution for the occupancy problem and its application to operon size prediction.

The problem of estimating the expected number of transcription units containing a specific number of genes arises in the context of operon size prediction in prokaryotic genomes, where operons are defined to be transcription units containing two or more genes. It turns out that this problem is identical mathematically to the balls in urns occupancy problem in probability theory. In that problem, a fixed number of indistinguishable balls are randomly placed in a known number of distinguishable urns, subject to the restriction that no urns may remain empty, and an estimate is desired for the expected number of urns containing a specific number of balls. In this paper we present a new simple technique for solving the occupancy problem when empty urns are allowed and extend it to the case when each urn must contain the same non-zero minimum number of balls. Treating transcription units as equivalent to urns, and genes as equivalent to balls, we then use that result to solve the problem of estimating the expected number of transcription units that contain a specific number of genes, and then apply that result to predicting the expected number of transcription units present in an entire genome. Since these predictions can be made for any completely sequenced and annotated prokaryotic genome, they provide a starting point for the comparison of regulatory complexity across such genomes.

Animals↗
PubMed2006

Invariance priors for Bayesian feed-forward neural networks.

Neural networks (NN) are famous for their advantageous flexibility for problems when there is insufficient knowledge to set up a proper model. On the other hand, this flexibility can cause overfitting and can hamper the generalization of neural networks. Many approaches to regularizing NN have been suggested but most of them are based on ad hoc arguments. Employing the principle of transformation invariance, we derive a general prior in accordance with the Bayesian probability theory for feed-forward networks. An optimal network is determined by Bayesian model comparison, verifying the applicability of this approach. Additionally the prior presented affords cell pruning.

Algorithms↗
PubMed2005

Diffusion MR imaging characteristics of the developing primate brain.

Diffusion-based magnetic resonance imaging holds the potential to non-invasively demonstrate cellular-scale structural properties of brain. This method was applied to fixed baboon brains ranging from 90 to 185 days gestational age to characterize the changes in diffusion properties associated with brain development. Within each image voxel, a probability-theory-based approach was employed to choose, from a group of analytic equations, the one that best expressed water displacements. The resulting expressions contain eight or fewer adjustable parameters, indicating that relatively simple expressions are sufficient to obtain a complete description of the diffusion MRI signal in developing brain. The measured diffusion parameters changed systematically with gestational age, reflecting the rich underlying microstructural changes that take place during this developmental period. These changes closely parallel those of live, developing human brain. The information obtained from this primate model of cerebral microstructure is directly applicable to studies of human development.

Algorithms↗
PubMed2004

Estimating the risk of collisions between bicycles and motor vehicles at signalized intersections.

Collisions between bicycles and motor vehicles have caused severe life and property losses in many countries. The majority of bicycle-motor vehicle (BMV) accidents occur at intersections. In order to reduce the number of BMV accidents at intersections, a substantial understanding of the causal factors for the collisions is required. In this study, intersection BMV accidents were classified into three types based on the movements of the involved motor vehicles and bicycles. The three BMV accident classifications were through motor vehicle related collisions, left-turn motor vehicle related collisions, and right-turn motor vehicle related collisions. A methodology for estimating these BMV accident risks was developed based on probability theory. A significant difference between this proposed methodology and most current approaches is that the proposed approach explicitly relates the risk of each specific BMV accident type to its related flows. The methodology was demonstrated using a 4-year (1992-1995) data set collected from 115 signalized intersections in the Tokyo Metropolitan area. This data set contains BMV accident data, bicycle flow data, motor vehicle flow data, traffic control data, and geometric data for each intersection approach. For each BMV risk model, an independent explanatory variable set was chosen according to the characteristics of the accident type. Three negative binomial regression models (one corresponding to each BMV accident type) were estimated using the maximum likelihood method. The coefficient value and its significance level were estimated for each selected variable. The negative binomial dispersion parameters for all the three models were significant at 0.01 levels. This supported the choice of the negative binomial regression over the Poisson regression for the quantitative analyses in this study.

Accidents, Traffic↗
PubMed2001

Effects of bromide on the formation of THMs and HAAs.

The role of bromide in the formation and speciation of disinfection by-products (DBPs) during chlorination was investigated. The molar ratio of applied chlorine to bromide is an important factor in the formation and speciation of trihalomethanes (THMs) and halogenacetic acids (HAAs). A good relationship exists between the molar fractions of THMs and the bromide incorporation factor. The halogen substitution ability of HOBr and HOCl during the formation of THMs and HAAs can be determined based on probability theory. The formation of HAAs, and their respective concentrations, can also be estimated through use of the developed model.

Acetic Acid↗
PubMedDate not supplied

Evaluation of safety of hypobaric decompressions and EVA from positions of probabilistic theory.

Formation and subsequent evolution of gas bubbles in blood and tissues of subjects exposed to decompression are casual processes in their nature. Such character of bubbling processes in a body predetermines probabilistic character of decompression sickness (DCS) incidence in divers, aviators and astronauts. Our original probabilistic theory of decompression safety is based on stochastic models of these processes and on the concept of critical volume of a free gas phase in body tissues. From positions of this theory, the probability of DCS incidence during single-stage decompressions and during hypobaric decompressions under EVA in particular, is defined by the distribution of possible values of nucleation efficiency in "pain" tissues and by its critical significance depended on the parameters of a concrete decompression. In the present study the following is shown: 1) the dimensionless index of critical nucleation efficiency for "pain" body tissues is a more adequate index of decompression stress in comparison with Tissue Ratio, TR; 2) a priory the decompression under EVA performed according to the Russian protocol is more safe than decompression under EVA performed in accordance with the U.S. protocol; 3) the Russian space suit operated at a higher pressure and having a higher "rigidity" induces a stronger inhibition of mechanisms of cavitation and gas bubbles formation in tissues of a subject located in it, and by that provides a more considerable reduction of the DCS risk during real EVA performance.

Aerospace Medicine↗
PubMed1987

An hypothesis about redundancy and reliability in the brains of higher species: analogies with genes, internal organs, and engineering systems.

The phenomena of behavioral resistance to massive brain damage and behavioral recovery from brain damage suggest there is redundancy in neural tissue. This paper uses basic concepts from probability theory and reliability engineering, as a first step toward more rigorously establishing the plausibility of the redundancy hypothesis. Exponential effects in the relevant formulas lead to results that are intuitively surprising. Thus, within a broad range of parametric assumptions related to lifespan and number of neurons or neural subsystems, it appears that the human brain may be at least twice as large as it would have to be for short-term survival. Simple reliability models suggest that redundancies are in parallel connections of smallest subsystems, such as individual neurons. Other implications of the basic formulas concern the relation between backed-up subsystem reliability and lifetime usage frequency for each subsystem, and the evolution of approximately equal allocation of lifetime reliability among components of a system. In addition, the paper briefly reviews more complex reliability engineering approaches. Redundancy as a reason for neural mass action is compared to other theoretical reasons for mass action in sensorimotor function and learning. Relationships of the present hypothesis to other theories of recovery from brain damage and to theories of regressive trophic phenomena in ontogeny are briefly discussed; it is suggested that as stages of ontogeny progress, both redundancy and flexibility in simpler behavioral functions are traded away for a larger, more differentiated repertoire of complex functions and memories.

Animals↗
PubMedDate not supplied

[Hypothyroid hypertrophic myopathy following mantle irradiation for Hodgkin's disease. A case].

The authors report a case of hypothyroid hypertrophic myopathy consecutive to mantle irradiation for Hodgkin's disease. A rise in TSH level is frequent after mantle irradiation and it justifies prolonged monitoring of these patients' thyroid function, in view of the risk of patent hypothyroidism and perhaps cancer. The patient's age, the pre-irradiation lymphography and the chemotherapy associated with radiotherapy are all factors that influence the incidence of thyroid dysfunction, but there is no agreement concerning their relative importance. Hypertrophic myopathies due to hypothyroidism are rare, and their dramatic clinical presentation contrasts with an almost normal muscle histology. Alterations of energy metabolism and changes in the properties of myosin induced by hormonal deficiency account for the muscular weakness of these patients. On the other hand, the mechanism of muscle hypertrophy remains controverted, the most probable theory being and increase in the number of myotubes. Following irradiation, notably for Hodgkin's disease, the frequency of hypothyroidism requires a regular and systematic laboratory follow-up. Replacement therapy must be instituted if the basal TSH level increases, even if the T4 level is normal.

Adult↗
PubMed1998

Elective cesarean hysterectomy vs elective cesarean section followed by remote hysterectomy: reassessing the risks.

Objective: The purpose of this study was to compare the risks of elective cesarean hysterectomy with the risks of elective cesarean section followed by remote hysterectomy.Methods: A census of elective cesarean hysterectomies (n = 31) and a random sample of 200 cesarean sections and 200 hysterectomies performed by the authors between 1987 and 1996 were evaluated. Only elective repeat and primary cesarean section patients without labor were selected for study (n = 86). Total abdominal hysterectomies were drawn from the sample (n = 60), excluding cancer cases, patients over 50 years old, and those with ancillary procedures other than adnexectomy and lysis of adhesions. General probability theory was used to calculate a predicted complication rate of cesarean section followed by TAH from the complication rates of the component procedures done independently. This predicted combined complication rate was then compared to the observed rate of complications from cesarean hysterectomy to evaluate the risks of the two alternative treatment regimens.Results: Elective cesarean section and total abdominal hysterectomy had complication rates of 12.8% and 13.4%, respectively. The predicted combined complication rate for elective cesarean section followed by TAH was 24.5%. The observed rate of complications for elective cesarean hysterectomy was much lower (16.1%). Although bleeding complications were similar for the two regimens, the rate of transfusion was higher for cesarean hysterectomy (13.0%) than for cesarean section (0%) and TAH (3.4%) alone. Eighty percent of the cesarean hysterectomy patients would have been candidates for autologous blood donation, had it been available.Conclusions: Elective cesarean hysterectomy has a lower risk of complications than elective cesarean section followed by remote abdominal hysterectomy and should be preferred. Transfusion risks are higher for cesarean hysterectomy but can be decreased by the use of autologous blood.

Journal Article↗
PubMedDate not supplied

Prediction of the formulation dependence of the glass transition temperatures of amine-epoxy copolymers using a QSPR based on the AM1 method.

A designer Quantitative Structure-Property Relationship, based upon molecular properties calculated using the AM1 semiempirical quantum mechanical method, was developed to predict the glass transition temperature of amine-cured epoxy resins based on the diglycidyl ether of bisphenol A. The QSPR (R2 = 0.9977) was generated using the regression analysis program, COmprehensive DEscriptors for Structural and Statistical Analysis. By applying an ad hoc treatment based on the elementary probability theory to the quantitative structure-property relationship analysis a method was developed for computing bulk polymer glass transition temperatures for stoichiometric and nonstoichiometric monomeric formulations. A model polymer was synthesized and found to validate our model predictions.

Journal Article↗
PubMed1997

A prospective study of a serum-pooling strategy in screening blood donors for antibody to hepatitis C virus.

BACKGROUND: To examine the feasibility and to perform a cost-benefit analysis of a pooling protocol of enzyme immunoassay (EIA) screening for antibody to hepatitis C virus (anti-HCV) under real conditions, a prospective study was carried out using sera from 1875 local blood donors. STUDY DESIGN AND METHODS: In the absence of knowledge of the anti-HCV reactions, the donor's sera were pooled into groups of five consecutive samples for testing by EIA. The dilution and final volume of the serum pool were adjusted to equal those recommended for single-serum EIA by the manufacturer of the test kit. The results obtained were compared with those of single-serum EIA to assess the feasibility of the pooling protocol. By applying probability theory, the percentage of reduction in the number of tests performed (L value) when the serum-pooling strategy was used was calculated for several anti-HCV seroprevalences and for varied sizes of pool. The calculations were performed on a computer using a program compiled by the authors. RESULTS: The results showed that seroprevalence was 2.24 percent (95% CI, 1.57-2.91%); the rate of false negativity was 0 (95% CI, 0-8.4%), the sensitivity of the pooling protocol was 100 percent (95% CI, 91.6-100.0%), the rate of false positivity was 0.8 percent (95% CI, 0-1.8%), and the specificity of the pooling protocol was 99.2 percent (95% CI, 98.2-100.0%). Cost-benefit analysis showed that the pooling protocol could save 69.3 percent of the cost. A table of L values can be used conveniently by serologists to determine the optimum pool size if estimates of seroprevalence are available. CONCLUSION: The pool EIA did not perform worse than individual EIAs, and the pooling strategy was markedly less expansive. The pooling protocol was recommended for screening of anti-HCV-positive subjects from large populations with low seroprevalence.

Adolescent↗
PubMed2004

Breakdown of Bell's theorem for certain objective local parameter spaces.

We show that the known proofs of Bell's inequalities contain algebraic manipulations that are not appropriate within the syntax of Kolmogorov's axioms for probability theory without detailed justification. Such justification can be achieved by a variant of the techniques used in Bell-type proofs but only for a subclass of objective local parameter spaces. It cannot be achieved for an extended parameter space that is still objective local and that includes instrument parameters correlated by both time and setting dependencies.

Journal Article↗
PubMed1969

Representations of weak and strong integrals in banach spaces.

We establish a representation of the Gelfand-Pettis (weak) integral in terms of unconditionally convergent series. Moreover, absolute convergence of the series is a necessary and sufficient condition in order that the weak integral coincide with the Bochner integral. Two applications of the representation are given. The first is a simplified proof of the countable additivity and absolute continuity of the indefinite weak integral. The second application is to probability theory; we characterize the conditional expectation of a weakly integrable function.

Journal Article↗
PubMed1974

A statistical study of optical rotation for synthetic d,l-copolypeptide solutions.

The right-handed helical fraction H(L) in a D,L-copolypeptide chain is evaluated by a simple probability theory for each L-fraction, p. The curves of optical rotation at a single wavelength against p for poly(gamma-benzyl-D,L-glutamate) and D,L-copolyleucine of a series of different D:L ratios in several positive helix-solvents are calculated with a modified semi-empirical Moffitt equation. From the comparison between the rotations calculated by us and observed by Downie et al., it is shown that to reproduce the observed rotations, the minimum number of right-handed helical nuclei or sequences of L-residues appropriate to the Moffitt equation are eight and four for degrees of polymerization 320 and 1860, respectively.

Journal Article↗
PubMed1996

Prime factors.

We use Voiculescu's free probability theory to prove the existence of prime factors, hence answering a longstanding problem in the theory of von Neumann algebras.

Journal Article↗
PubMed1996

Randomness and degrees of irregularity.

The fundamental question "Are sequential data random?" arises in myriad contexts, often with severe data length constraints. Furthermore, there is frequently a critical need to delineate nonrandom sequences in terms of closeness to randomness--e.g., to evaluate the efficacy of therapy in medicine. We address both these issues from a computable framework via a quantification of regularity. ApEn (approximate entropy), defining maximal randomness for sequences of arbitrary length, indicating the applicability to sequences as short as N = 5 points. An infinite sequence formulation of randomness is introduced that retains the operational (and computable) features of the finite case. In the infinite sequence setting, we indicate how the "foundational" definition of independence in probability theory, and the definition of normality in number theory, reduce to limit theorems without rates of convergence, from which we utilize ApEn to address rates of convergence (of a deficit from maximal randomness), refining the aforementioned concepts in a computationally essential manner. Representative applications among many are indicated to assess (i) random number generation output; (ii) well-shuffled arrangements; and (iii) (the quality of) bootstrap replicates.

Journal Article↗
PubMed2004

Metrics for comparing regulatory sequences on the basis of pattern counts.

MOTIVATION: Upstream sequences contain short motifs, which mediate transcriptional regulation by specifically binding different transcription factors. The presence of common motifs in the regulatory regions of two genes might be considered as a clue for a potential co-regulation. A pattern count-based (dis)similarity metric between sequences could thus be used to classify genes according to their putative regulatory properties. RESULTS: We present here several metrics which rely on probability theory, and which aim at comparing sequences on the basis of pattern counts. We compare these metrics to several classical dissimilarity and similarity metrics, and illustrate their behaviour with a biological example.

Algorithms↗